Did some bullet testing today, one mfg vs. another, all else in loads equal, both 405gr, .458" diam in a 45-70, approx 62 gr Goex 2F, two .30 paper wads, and the bullet, about .2" worth of compression, not much crimp. I am shooting them in a Pedersoli RB, heavy bbl. one of the bullets displayed terrible accuracy and a significant keyhole, the other showed much better accuracy, but on close examination of the targets when I got home, there is evidence of lead wiping on one side of the hole on some of the hits, worse with one of the bullets than the other, but evidence of wobble on both. Is the Pedersoli twist rate too fast for 405 gr??? Do I need more lube?? I have never had such a problem before, can anyone give me some insight???? thanks

Don't know much about the load of powder. I can say if you're gonna shoot cast, whether your own or purchased, slug your bore and buy or size to .001-.002" over groove size. Hardness is not near the factor some think it is, but fit is absolutely the most important factor in shooting cast bullets. GW

edit: Personally I would paper patch for that cartridge with cast, but that's a whole new ball game. GW

Pedersoli barrels run .450/458 and need at least a .459 or .460 cast bullet to perform adequately. The 45/70 has a twist of 1:18" which will stabilise bullets up to a Paul Jones 545gn that I use in mine for long range work.

Standard factory moulds like Lyman Postell don't readily cast oversized projectiles that you require! I have a Henley & Gibbs 420gn that casts .460 dia and these shoot well in a number of my 45/70's.

Further study reveals a couple more details, the "poor" bullet has four grease grooves, the first within 1/16" of the base, the "good" bullet has one, about 1/2" from the base, then, both are bevel based(I'm thinking this is a no-no in BPCR?) and I'm only using two paper wads under the bullet, so I'm thinking the keyholing is a result of the base and wad,(ergo, gas cutting) BECAUSE, I drove a .490" RB down the bbl, miked at .458", drove a 255 gr soft pistol bullet down the bore after "bumping it up" with a hammer, it miked .458" and I took one of the "bad" bullets and drove it nose first down the bbl and it miked the same and was FULLY engraved, and before driving it down it miked about .460" , same as the good bullet.
So I have ordered some .060" veggie wads and will try those and will look for a flat based bullet to use. Any other suggestions of stuff to look at??

You need very soft alloy to shoot with black powder .30-1 to 20-1 works good .All the comercial cast bullets are for smokeless unless they state there alloy .Bevel bases for sure wont help your accuracy.Do some google searches for any one making bullets for Black powder use or cast your own . Buffalo Arms in Idaho is a good source . Arnie

I agree with Hiwall....only first make sure your bullets are designed for BP....all that I have ever used are flat based.
Second....make sure the alloy is a BP alloy....softer than smokeless bullets.
Third ...make sure the BPCR bullet has adequate lube grooves.
And finally....make sure it is slightly larger than your rifle's bore.

The only case of a tumbling bullets in a BPCR I ever witnessed was with a commercial 405 GR bullet made for smokeless which had a .457 dia. This bullet even whistled as it made its way down range! The rifle was a Shiloh Sharps which shot much better with hand poured 500 grain bullets from a LYMAN BPCR mould.

This does sound like it could be caused by gas escape reducing the size of the bullet. Have you recovered any bullets in good shape from the target? They might show reduced diameter, or normal-looking rifling engraving on one side only of the bullet. The same might apply if they are cast bullets with off-centre cavities. Even a slow-twist rifle spins the bullet fast enough for centrifugal force to be strong in this situation.

I once bought a P14 Enfield for converting to a .300H&H, and tried a few shots with my .308 jacketed bullets in the original .312 groove barrel. They invariably keyholed, although bullets don't need more than a fraction of the engagement they would find with a .300 land, 305 groove barrel, if such a thing existed. The problem was that gas escape through the .0035 space in each groove reduced the bullet, and it ended up pressed against one side of the bore.

In this situation, there is another source of inaccuracy, even if the bullet doesn't keyhole. When the centre of mass of the bullet is off-centre, it is actually travelling in a small-diameter helical curve, of the same pitch as the rifling. Newton's First Law states that an object will travel in a straight line unless it is acted up by an external force. As soon as that bullet leaves the muzzle, the rifling is no longer making it travel in that helix. So it flies off squint, in the direction that centre of mass was moving on exiting.

Basically you are shooting a black powder muzzle loader that happens to use a cartridge. Slug the bore, use a flat based bullet lubed with SPG at least 2 thou over bore and made of pure lead. Pure lead will bump up to fill the bore and produce excellent accuracy and killing power.

Remember "back in the day" the men who were extreme accuracy nuts used false muzzles to muzzle load their cartridge rifles, In a 45 caliber black powder rifle the only real advantage for those men was a better priming system and a gun far easier to clean, either "on the line" or after the shoot was over.

Actually going to try the new Alliant BP (heresy!) in my Tom Brown built Whitworth replica .452 MZ, just because you can shoot 20 rather than 5 before getting out the cleaning tools.
(20 vs 5 is based on a Browning 1885 High Wall 45-70)

Those last two digits are there for a reason; to load 70 grs. of blackpowder! Bevel bullets ARE NOT the way to go....use a good flat-based bullet of the right alloy. I use 1-40 alloy and it works quite well delivering great accuracy! If you're going to use grease groove bullets a diameter of .458 will upset well and give excellent accuracy provided you do your part. Use at least a .060" thick OPW atop the powder and wipe off any excess lube from the base of the bullet. As already stated....smokeless alloyed bullets are a no no and so is a smokeless type lube. Use a lube designed for blackpowder. I have used up to 76 grs. of Swiss 3F powder in the 45/70 and it gives good accuracy. Drop that much through a 30" drop tube and it will fit. DO NOT compress the powder charge using the bullet or you will not be able to hit due east!!

My rifle did the same thing , using 500 gr lyman 457125 mold Hodgton T7 3F I found that I was deforming the bullet pressing it into the brass with to much powder and using milk carten wads under it , So I lowered the charge ,used newspaper cut .460 under bullet , and milk carten under newspaper Wax side to news paper so it don't stick to bullet base , I lube with 1000 wonder lube, and lube the barrel before shooting to help clean barrel better between shots ,T7 makes cleaning barrel a joy between shots .

Try about 60 gr of 2F powder, seat a Walter's .030" wad on top of the powder and compress with compression stem till you can get that bullet in and seated to the bottom of the drive band without smashing the nose. Great bullet and good accuracy with 2Fg powder...or Swiss 1.5.

when you load, make sure your bullet is not too hard....soft lead will upset better. use enough SPG to compensate
OK>......here is your problem...use the regular wad, verggie type is fine, but then use TWO newspaper wads. TWO....your veggie wad is sticking to the bullet. two paper wads under the bullet prevent this. they just separate and won't go down range. I had the same problem and this cured it forever. improved accuracy too. . good luck...Ken

I had Beartooth bullets sized out to .460 for the Pedersoli rifles. I also slug those barrels and fire lapped them with Marshalls guidance. It sure made a big difference in our 444 Marlin and 45/70 Marln's. Cut the groups down better than half the MOA.